How can I train a deep learning model to predict a matrix?
You could use a CNN or Fully Connected Network and output a matrix of size 8*2*2. The first 8*2 matrix is the real number and the second is the imaginary number. Example code below uses keras.

'''
input: numpy array of shape(batch_size,input_dim_0,input_dim_1,1)
Y: keras tensor of shape(batch_size,8,2,2)

'''

model = Sequential()
model.add(Conv2d(64,3,input_dim =(input_dim_0,input_dim_1,1))
model.add(Conv2d(64,3)
model.add(Conv2d(2,3)

model.compile(loss='MSE',metrixs=['accuracy'])
model.fit(input,Y)